Process of bleaching detergent salts



PROCESS OF BLEACHING DETERGENT SALTS- Irving J. Krems, Vienna, Austria,and Frederick William Gray, Belleville, N.J., assignors toColgate-Palmolive Company, New York, N.Y., a corporation of Delaware NoDrawing. Filed June 4, 1958, Ser. No. 739,666

3 Claims. (Cl. 260-505) The present invention relates to ozone-bleachingof normally solid water-soluble higher alkylbenzenesulfonate detergentswhich contain oxidizable color bodies.

Higher alkylbenzenesulfonate detergents are frequently somewhatdiscolored by the presence therein of color bodies subject to oxidationand decoloration by gaseous ozone. However, as the sulfonate is normallya solid material, it is diflicult to assure eflicient and completecontact of the gaseous ozone with the color bodies which are dispersedthroughout the sol-id detergent. However, it has now been discoveredthat by contacting a higher alkylbenzenesulfonate detergent containingoxidizable color bodies with gaseous ozone in the presence of criticalproportions of water and total solids, these detergents may beeffectively bleached.

The present process is highly effective and economical, and avoids thecorrosion experienced when using chlorinebased bleaching agents such ashypochlorites. In addition, residual excess bleaching agent is innocuousand easily removed if desired. Development of objectionable odors suchas sometimes follows hypochlorite bleaching, has not been found tooccur.

In accordance with the present invention, a process for bleaching anormally solid water-soluble higher alkylbenzene-sulfonate detergentwith gaseous ozone comprises admixing a solid water-soluble higheralkylbenzenesulfonate detergent containing oxidizable color bodies withwater in an amount sufficient to form an aqueous mixture containingabout 40 to 60% water and about 60 to 40% total solids, said detergentcomprising at least about 10% of said solids, and intimately contactingsaid aqueous mixture with gaseous ozone in an amount sufiicient tooxidize said oxidizable color bodies and thereby produce said higheralkylbenzenesulfonate detergent in bleached form.

The detergents which are bleached according to the present process arewell-known to the art, being normally solid, water-soluble salts ofhigher alkylbenzenesulfonic acids in which the alkyl group contains fromabout 10 to 16 carbon atoms, suitable alkyl substituents beingexemplified by the decyl, dodecyl, and pentadecyl radicals or mixturesthereof such as may be prepared from polymerized lower olefins, e.g.tetrapropylene and pentapropylene, as well as branched and straightchain substituents prepared from cracked parafiin waxes, kerosene andthe like. Preferred detergents are the sodium salt of tetrapropyleneandpentapropylene-benzenesulfonic acids.

Although the preferred salt is the sodium salt, any water-soluble,normally solid salt stable to ozonolysis may be used. Thus, within theambit of the invention are the alkali metal and alkaline earth salts,i.e. the potassium, lithium, magnesium, and calcium salts; as Well asother metallic and non-metallic salts such as the zinc salts andammonium salts.

The ozone employed may be prepared in the customary manner, e.g. fromeither air or pure oxygen by means of electric discharge. Because of itslower cost and the proportionately better conversion of oxygen to ozoneachieved when using air rather than pure oxygen as an nited StatesPatent oxygen source, it is preferred to employ air as a startingmaterial. Typically, the gaseous medium employed for bleaching containsfrom about 0.25 to 10% or more ozone, and bleaching may be carried outat a temperature within the range of about 15 C. to 70 C. and at anydesired pressure (preferably atmospheric) either batchwise orcontinuously. In carrying out the present process, the gaseous ozone isdispersed throughout and intimately contacted with a suitable higheralkylbenzenesulfonatecontaining aqueous magma or slurry.

The weight ratio of ozone to sulfonate detergent employed is related tothe proportion and nature of the oxidizable color bodies associated withthe detergent and the ultimate acceptable color, and is best establishedin any one instance by experiment. However, normally this ratio willvary from about 1:100 to 1:1000.

The ratio of total solids to water employed in the magma or slurry usedin carrying out the present process is critical. It has been found thatif the level of total solids drops substantially below about 40% byweight (i.e. if more than about 60% by weight of water is present),bleaching efficiency is considerably diminished, and in addition severefoaming, which may cause the bleaching system to flood or overflow, islikely to be encountered. On the other hand, the total solids content ofthe mixture being bleached must be less than 60% in order to maintain afiowable, pumpable state at ordinary temperatures. A preferred range oftotal solid contents is from 45% to 50% the balance being water. Thetotal solids will contain at least about 10% and typically 10% to 95% ofhigher alkylbenzenesulfonate, the remainder being principally inorganicsalts such as sodium sulfate, and oxidizable color bodies. Preferablythe total solids will contain from about 40% to about 85% higheralkylbenzenesulfonate.

The following examples are given to additionally illustrate the natureof the present invention and it will be understood that the invention isnot limited thereto.

Example I An aqueous detergent slurry is placed in a closed vesselequipped with an agitator, a thermometer, a gas inlet which extends tothe bottom of the vessel, and a gas outlet vent. The slurry contains 50%water and 50% total solids, the solids consisting of about 18% sodiumsulfate, about 1% of color bodies and unsulfonated material, andapproximately 81% by Weight sodium pentadecylbenzene sulfonate.

Air is electrically ozonized and is then passed through the inlet intothe slurry, which is agitated. The gas input rate is approximately 10liters per hour, the gas being at room temperature and at merelysufiicient pressure to cause it to flow through the ozonizing andbleaching systems. Each liter of ozonized gas employed containsapproximately 30 milligrams of ozone.

During bleaching, only slight foaming occurs, and the temperature of theslurry increases from room temperature to about 40 to 45 C.

The gas outlet vent is connected to a trap containing a solution ofpotassium iodide which disposes of non-utilized ozone. The trap in turnis vented to the atmosphere through a gas meter. Bleaching is carriedout by introducing the ozonized gas into the slurry until it has beentreated with 360 milligrams of ozone per grams of sulfonate salt. Theunreacted portion of the gas bubbles through the slurry and leaves thevessel by means of the outlet vent. Of the total 360 milligrams of ozoneintroduced into the slurry, 340 are consumed by the slurry and 20milligrams are lost in the vented gas. At the end of the bleaching step,the ozonizer is shut off and the ozonizer, bleaching vessel, andremainder of the system is flushed out with a liter of air.

The slurry is then removed from the vessel and is roll dried. The Klettcolor ofa 5% aqueous solution of the dried product is 89 as compared toa Klett color of 212 characterizing a 5%.aqueous solution of asimilarlydried but. unbleached portion of the original sulfonate. This alsocompares 'favorably with a Klett colorof. 115 characterizing a sample ofthe original sulfonate which has been bleached with 1.6. grams of sodiumhypochlorite. per

100, grams of sulfonate salt.

Example 11 The process of Example 1 is repeatedemploying a sample of thesame batch of sodium pentadecylbenzenesulfonate. The slurry is dilutedto atotal. solids content of 39%, the remainder being water. Oxygenisemployed in place of air for ozonolysis, and each liter of the streamof ozonized oxygen contains about '60 milligrams oiozone. Bleaching iscarried out using a total of 350 milligrams of ozone per 100 grams ofsulfonate salt. -A

.liter of oxygen is used to flush the system afterbleach- -ischaracterized by a Klett color of 111.

Example III An aqueous slurry containing 53% "water and 47% solids isbleached in the manner set forth in Example II. The slurry solidscontain 11% sodium sulfate, about 1% of color bodies and unsulfonatedorganic material,.and the remainder is sodiumpentadecylbenzenesulfonate. A toal of 740 milligrams of ozone per 100grams ofsulfonate. are passed through the slurry. .After the first 150milligrams per 100grams of sulfonatehave been passed through theslurry,a noticeable improvement in color occurs. -After using 230 milligramsper 100. grams of sulfonate, the sulfonate is quite white in colorandthereafter there is little visible. improvement as further ozone .isadmitted. Of the 740 milligrams per 100: grams of sulfonate which areused, 680 are consumed by the slurry and 60 are lost in the vented gas.

The bleached product exhibits a Klett color of 85, which compares with165 when the original slurry is dried without bleaching and'96 when itis bleached with 11.6 grams of sodium hypochlorite per 100 grams ofsulfonate salt.

Specimens of the sodium (or other water soluble)'salt ofdodecylbenzenesulfonic acid containing oxidizable color bodies may bedirectly substituted for the-sulfonate detergent of Examples 1, II andIII.

The critical nature ofthe total solids content of the slurry beingbleached may be shown by adding water to the slurry of Example 111 untilit contains 94% water and only 6% total solids. When the bleachingprocedure of Example 111 is applied to this slurryycon'siderable foamingoccurs and even though 1400 milligrams of ozone per 100 grams ofsulfonate are used and the slurry consumes all 1400 milligrams, thedried product is characterized by a Klett color of 115.

, higher alkylbenzenesulfonate detergent in which the alkyl groupcontains from about 10 to 16 carbon atoms and which detergent containsoxidizable colorbodies with water in an amount sufiicient to form anaqueous slurry consisting essentially of 40% to 60% water and about 60%to 40% total solids, said total solids containing at least about 10% ofsaid higher alkylbenzenesulfonate detergent, and intimately contactingsaid aqueousslurry with gaseous ozone in an -amount-suflicient tooxidize said oxidizable color bodies and thereby produce said higher'alkylbenzenesulfonate' detergent in bleached form.

2. "A process for bleaching a solid water-soluble higheralkylbenzenesulfonatedetergent with a gaseous medium containing fromabout 0.25- to 10%' ozone which comprises admixing a solidwater-soluble'higher alkylbenzeue 'sulfonate detergent in which thealkyl'group contains from about 10 to 16 carbon atoms and whichdetergent contains oxidizable color bodies with water in an amountsufi'icient to form an aqueous slurry consisting essentially of about40% to 60% water and about 60% to 40% total solids,'said total solidscontaining at least about 10%" of said higher alkylbenzenesulfonatedetergent, and intimately contacting said aqueous'slurrywith an amountof aggaseous medium containing about 0.25 to 10% ozone siifiicient to Joxidize said oxidizable color'bodies and thereby produce said higheralkylbenzenesulfonate detergem in a bleachedform.

3. A'process for bleaching a sodium salt of a higher alkylbenzenesulfonic acid with gaseous ozonewhich comprises admixing anormally solid salt of ahigher alkylbenzenesulfonic' acid in which thealkyl' group contains from about 12 to 15 carbon atoms and'whichdeter-'gentcontains oxidizable color bodieswith -water in'an amount sufficientto form an aqueous slurry consisting essentially of from about'45 to50%total solids, the balance being water; said total solids containingabout 55 to 60% of said higher alkylbenzenesulfonate, theremainderthereof being principally inorganic salt and oxidizable color bodies;and intimately contacting said aqueous slurry at a temperature of about15 C. to C. with an amount of a gaseous medium containing from about 1%to 4% ozone sufficient to oxidize said oxidizable color bodies andthereby produce said higher alkylbenzenesulfonate detergent in ableached form.

ReferenceslCited in thefile of this patent 1 UNITED STATES PATENTS2,842,588 Honeycutt July 8, 1958

1. A PROCESS FOR BLEACHING A NORMALLY SOLID WATERSOLUBLE HIGHERALKYLBENZENESULFONATE DETERGENT WITH GASEOUS OZONE WHICH COMPRISESADMIXING A SOLID WATER-SOLUBLE HIGHER ALKYLBENZENESULFONATE DETERGENT INWHICH THE ALKYL GROUP CONTAINS FROM ABOUT 10 TO 16 CARBON ATOMS ANDWHICH DETERGENT CONTAINS OXIDIZABLE COLOR BODIES WITH WATER IN AN AMOUNTSUFFICIENT TO FORM AN AQUEOUS SLURRY CONSISTING ESSENTIALLY OF 40% TO60% WATER AND ABOUT 60% TO 40% TOTAL SOLIDS, SAID TOTAL SOLIDSCONTAINING AT LEAST ABOUT 10% OF SAID HIGHER ALKYLBENZENESULFONATEDETERGENT, AND INTIMATELY CONTACTING SAID AQUEOUS SLURRY WITH GASEOUSOZONE IN AN AMOUNT SUFFICIENT TO OXIDIZE SAID OXIDIZABLE COLOR BODIESAND THEREBY PRODUCE SAID HIGHER ALKYLBENZENESULFONATE DETERGENT INBLEACHED FORM.